The invention relates in general to respiration and particularly pertains to a respirator and respiratory method intended for recirculating operation, using an expiration bag, in which an internal tension spring is provided for compressing the expiration bag, and also inspiration bag, which can be connected to a respiraticn gas source, having a CO.sub.2 -binding chemical cartridge and an oxygen source arranged in the respiratory circuit between inspiration bag and the expiration bag.
A similar respirator has become known from West German Patent Specification No. 24,21,297 in which the prior-art respirator has an expiration bag, whose mobile, opposite end faces can be drawn together by an internal tension spring, so that the contents of the filled expiration bag are pressed through the chemical cartridge in the expiration branch of the respiratory circulating line. The positive pressure occurring in the expiration line disappears during the flow through the chemical cartridge, so that the user of the respirator must inhale the regenerated expired air during the inspiration phase, while a vacuum is being generated. The vacuum thus generated in the inspiration system may lead to the undesired penetration of toxic substances into the respiratory circuit in the case of leakage of the ambient air that may be enriched with toxic substances. The construction and use of the expiration bag of the prior-art respirator is unable to guarantee a positive pressure in the entire respiratory circuit, because the positive pressure in the expiration bag cannot extend into the inspiration branch due to the check valve, and it will be abolished by the downstream regenerating cartridge during the passage through the cartridge.